The best way to introduce aroma oils into the steam shower is through an aroma pump system or carefully manually mist them into the environment with a spray bottle.
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If you desire to use herbs, just simply having them in the heated environment will increase their aroma. The rooms are hotter closer to the ceiling and cooler near the floor so you might put a container of dry herbs on a shelf.
Automated through the steam line with a pump is the best way to go for consistent smell and strength every time.
Our AromaMist Essential Oils are organic. Aroma Oils